Re: [RFC 09/14] xen/xsm: flask: MSI is PCI specific

[Daniel De Graaf <dgdegra@tycho.nsa.gov>]

On 03/12/2014 12:16 PM, Julien Grall wrote:
> MSI is not yet support on ARM and will break the compilation when XSM_ENABLE=y.
>
> Signed-off-by: Julien Grall <julien.grall@linaro.org>
> Cc: Daniel De Graaf <dgdegra@tycho.nsa.gov>

I am assuming that IRQs on ARM are generally allocated in a static manner for
a given board, so that a security policy based on their numeric values would
be effective. If IRQs above nr_static_irqs are dynamic as on x86, it may be
necessary to resolve them in some way. Since this resolution would naturally
be split into a separate patch, in either case this patch is

Acked-by: Daniel De Graaf <dgdegra@tycho.nsa.gov>

> ---
>   xen/xsm/flask/hooks.c |   72 +++++++++++++++++++++++++++++++++++--------------
>   1 file changed, 52 insertions(+), 20 deletions(-)
>
> diff --git a/xen/xsm/flask/hooks.c b/xen/xsm/flask/hooks.c
> index 65343f3..56c7645 100644
> --- a/xen/xsm/flask/hooks.c
> +++ b/xen/xsm/flask/hooks.c
> @@ -19,7 +19,9 @@
>   #include <xen/errno.h>
>   #include <xen/guest_access.h>
>   #include <xen/xenoprof.h>
> +#ifdef HAS_PCI
>   #include <asm/msi.h>
> +#endif
>   #include <public/xen.h>
>   #include <public/physdev.h>
>   #include <public/platform.h>
> @@ -100,7 +102,6 @@ static int domain_has_xen(struct domain *d, u32 perms)
>
>   static int get_irq_sid(int irq, u32 *sid, struct avc_audit_data *ad)
>   {
> -    struct irq_desc *desc = irq_to_desc(irq);
>       if ( irq >= nr_irqs || irq < 0 )
>           return -EINVAL;
>       if ( irq < nr_static_irqs ) {
> @@ -110,15 +111,21 @@ static int get_irq_sid(int irq, u32 *sid, struct avc_audit_data *ad)
>           }
>           return security_irq_sid(irq, sid);
>       }
> -    if ( desc->msi_desc && desc->msi_desc->dev ) {
> -        struct pci_dev *dev = desc->msi_desc->dev;
> -        u32 sbdf = (dev->seg << 16) | (dev->bus << 8) | dev->devfn;
> -        if (ad) {
> -            AVC_AUDIT_DATA_INIT(ad, DEV);
> -            ad->device = sbdf;
> +#ifdef HAS_PCI
> +    {
> +        struct irq_desc *desc = irq_to_desc(irq);
> +        if ( desc->msi_desc && desc->msi_desc->dev ) {
> +            struct pci_dev *dev = desc->msi_desc->dev;
> +            u32 sbdf = (dev->seg << 16) | (dev->bus << 8) | dev->devfn;
> +            if (ad) {
> +                AVC_AUDIT_DATA_INIT(ad, DEV);
> +                ad->device = sbdf;
> +            }
> +            return security_device_sid(sbdf, sid);
>           }
> -        return security_device_sid(sbdf, sid);
>       }
> +#endif
> +
>       if (ad) {
>           AVC_AUDIT_DATA_INIT(ad, IRQ);
>           ad->irq = irq;
> @@ -825,21 +832,34 @@ static int flask_map_domain_pirq (struct domain *d)
>       return current_has_perm(d, SECCLASS_RESOURCE, RESOURCE__ADD);
>   }
>
> +static int flask_map_domain_msi (struct domain *d, int irq, void *data,
> +                                 u32 *sid, struct avc_audit_data *ad)
> +{
> +#ifdef HAS_PCI
> +    struct msi_info *msi = data;
> +
> +    u32 machine_bdf = (msi->seg << 16) | (msi->bus << 8) | msi->devfn;
> +    AVC_AUDIT_DATA_INIT(ad, DEV);
> +    ad->device = machine_bdf;
> +
> +    return security_device_sid(machine_bdf, sid);
> +#else
> +    return -EINVAL;
> +#endif
> +}
> +
>   static int flask_map_domain_irq (struct domain *d, int irq, void *data)
>   {
>       u32 sid, dsid;
>       int rc = -EPERM;
> -    struct msi_info *msi = data;
>       struct avc_audit_data ad;
>
> -    if ( irq >= nr_static_irqs && msi ) {
> -        u32 machine_bdf = (msi->seg << 16) | (msi->bus << 8) | msi->devfn;
> -        AVC_AUDIT_DATA_INIT(&ad, DEV);
> -        ad.device = machine_bdf;
> -        rc = security_device_sid(machine_bdf, &sid);
> +    if ( irq >= nr_static_irqs && data ) {
> +        rc = flask_map_domain_msi(d, irq, data, &sid, &ad);
>       } else {
>           rc = get_irq_sid(irq, &sid, &ad);
>       }
> +
>       if ( rc )
>           return rc;
>
> @@ -858,18 +878,30 @@ static int flask_unmap_domain_pirq (struct domain *d)
>       return current_has_perm(d, SECCLASS_RESOURCE, RESOURCE__REMOVE);
>   }
>
> +static int flask_unmap_domain_msi (struct domain *d, int irq, void *data,
> +                                   u32 *sid, struct avc_audit_data *ad)
> +{
> +#ifdef HAS_PCI
> +    struct msi_info *msi = data;
> +    u32 machine_bdf = (msi->seg << 16) | (msi->bus << 8) | msi->devfn;
> +
> +    AVC_AUDIT_DATA_INIT(ad, DEV);
> +    ad->device = machine_bdf;
> +
> +    return security_device_sid(machine_bdf, sid);
> +#else
> +    return -EINVAL;
> +#endif
> +}
> +
>   static int flask_unmap_domain_irq (struct domain *d, int irq, void *data)
>   {
>       u32 sid;
>       int rc = -EPERM;
> -    struct msi_info *msi = data;
>       struct avc_audit_data ad;
>
> -    if ( irq >= nr_static_irqs && msi ) {
> -        u32 machine_bdf = (msi->seg << 16) | (msi->bus << 8) | msi->devfn;
> -        AVC_AUDIT_DATA_INIT(&ad, DEV);
> -        ad.device = machine_bdf;
> -        rc = security_device_sid(machine_bdf, &sid);
> +    if ( irq >= nr_static_irqs && data ) {
> +        rc = flask_unmap_domain_msi(d, irq, data, &sid, &ad);
>       } else {
>           rc = get_irq_sid(irq, &sid, &ad);
>       }
>


-- 
Daniel De Graaf
National Security Agency